WO1989011159A1

WO1989011159A1 - Display device

Info

Publication number: WO1989011159A1
Application number: PCT/US1989/001977
Authority: WO
Inventors: William P. Parker
Original assignee: Parker William P
Priority date: 1988-05-10
Filing date: 1989-05-09
Publication date: 1989-11-16
Also published as: EP0417195A4; JPH03505144A; JP3080628B2; US4956577A; EP0417195B1; KR900702560A; EP0417195A1; AU625458B2; RU2063066C1; HK1007832A1; DE68925968D1; CA1316689C; AU3763889A; DE68925968T2; ATE135493T1

Abstract

A gas discharge display apparatus (10) in the form of an electroluminescent gas filled panel adapted for quickly and inexpensively making a durable and robust luminous sign using image patterns transferred to the panel by painting, silkscreening, stencilling, lithography, or the like. The apparatus generally includes a pair of substantially parallel spaced apart rigid plates (12, 14) or sheets, enclosing an electroluminescent gas, and having variously located and kinds of conductive surface coating (26, 28) used as electrodes for energizing the enclosed electroluminescent gas. A plasma glow discharge is interactively obtained in the chamber by placing a ground coupled conductive member, such as a human hand, proximal to the chamber opposite the conductive surface.

Description

DISPLAY DEVICE

BACKGROUND OF THE DISCLOSURE

The invention is in the field of luminous displays and signs, and more particularly relates to gas plasma display devices.

The production of light by the passage of electricity through gases is a well known phenomenon. Devices utilizing this phenomenon have been widely developed in the form of plasma display devices which display specific numerals, characters, symbols, graphics, and the like. The neon sign is an example of a gas discharge display device, typically including an elongated glass tube filled with neon and a pair of excitation electrodes disposed at opposite ends of the tμbe. In this example, the rigid tube, or envelope, defines the shape of the^' illumination pattern. This shape is established at the time of manufacture, and cannot be changed.

Other prior art gas discharge display devices may include a plurality of shaped character electrodes in direct or close contact with an electroluminescent gas within a glass envelope, for example, Nixie tubes. In such devices, selected ones of the shaped electrodes may be energized to obtain a desired character display. Again, the shape of the illumination is predetermined by the shape of the electrode which is established at the time of manufacture of the device. Still other forms of prior art gas discharge display devices include dielectric-bounded, gas-filled character-shaped channels within an envelope, with a suitable set of energizing 5 electrodes. As in U.S. Patent No. 3,621,332, a plurality of such channels may be established within a single envelope, with electrodes being arranged for selective activation of one channel at a time. Alternatively, as in U.S. Patent No. 4,584,501, a

ID. single elongated channel may be formed in one plate o£ a; two glass plate sandwich arrangement, with energizing channels in an adjacent plate. All of these arrangements are suitable for displaying indicia, but as with the earlier discussed prior art-,

15 the shape of the display, i.e. the channel configuration, is determined at the time of manufacture of the device.

Yet other prior art gas discharge devices include generally similar display configurations, but

20 have an addressable matrix in which selected dot regions may be selectively energized. For example, as shown in U.S. Patent No. 4,035,690, selected ones of overlapping orthongal sets of electrodes may be energized to generate a desired dot matrix

25 character. In that patent, the electroluminescent gas is confined to the interior of a plurality of dielectric spheres disposed between the sets of electrodes. With the dot addressible matrix, substantial flexibility is provided in that any dot

30 pattern graphics may be displayed, for example using conventional bit-mapped graphics technigues. However, as with the other above mentioned prior art, all possible display patterns, i.e. the electrode overlap regions, are established at the time of manufacture of the device.

Yet another form of prior art gas discharge device is disclosed in U.S. Patent No. 3,629,654. As shown in that patent, a pair of opposed, spaced apart plates are mutually sealed at their perimeter to establish an electroluminescent gas filled cell. A transparent conductive coating is disposed on one outer surface of the cell. A movable external sheet having predetermined shaped conductive regions is pressed against the other outer surface of the cell and an ionizing signal is applied across the conductive coating and the conductive region of the external sheet to generate a visible discharge in the cell having the shape of the conductive regions of the external sheet. This two-element display thus requires a means for positioning the external sheet relative to the cell in order to establish an image.

In the prior art there are many known techniques and circuits for the interactive control of luminous and lighting devices. Many of these are commercially available as "touch control" light dimmers or switches. These generally employ circuitry that senses an external field or capacitance, as that of a human body or any of its parts, either by close proximity or by direct contact with a circuit element. In these devices, the effect of the application of the external field or capacitance is an alteration of the circuitry's operating state, leading to an offset voltage or current internal to 5 the circuit. This voltage or current offset is then applied to some interconnected lighting device, i.e., an incandescent lightbulb, thus changing its brightness in a response to either the duration or character of the externally applied influence.

IDG The term "interactive" here applies to the nature of the control mechanism, it being the control loop formed by the person initiating or continuing the influence on the circuit and the circuit's response in changing the light output of the lighting

15 device, with feedback between the light output of the lighting device and the person. The interaction of the person with the (control mechanism/lighting device) combination results in a change in the operating parameters of the combination, i.e., a

20 modification of the light output of the lighting device. Lighting control devices of this type may be characterized as indirect interacting, due to the indirect nature of the control influence on the lighting device itself.

25 It is also known in the prior art to directly interact with the method of light production, and thus directly control the lighting device. By way of example, there are certain gas plasma artistic works, such as those of the present

30 inventor, in which an electroluminescent gaseous medium is contained in an enclosed gas tight chamber and disposed about an electrode centrally located within the chamber. When the electrode is suitably energized, a luminous plasma discharge is established from the electrode, through the chamber to a reference potential outside the chamber. With such devices, when a person touches the chamber surface, the person's body, or some part of thereof, acts as a capacitor plate and thereby allowing the passage of alternating current between the electrode and the reference potential along field lines that are directly related to the body capacitance and its point of application to the chamber wall. This capacitor effect acts as charging means for the luminescent gas, producing what is termed a capacitive discharge. When in use, the device responds to the proximity of the body, or any other such effective capacitor plate, in direct correspondence to it capacitance, and a luminous display is produced that is directly related to its distance from the central electrode.

It is an object of the present invention to provide an improved plasma display device.

Another object is to provide an improved plasma display device which may be user-programmed for the display of a desired image.

Yet another object is to provide an improved plasma display which may be economically and efficiently configured to display a desired image.

Another object is to provide an improved plasma display device which may be interactively controlled, for example by a person's body capacitance, to establish a luminous plasma display. -6-

SUMMARY OF THE INVENTION

Briefly, the present invention is an electroluminescent gas filled double walled panel with the provision for electrode surfaces on both 5 sides of the gas space, which will allow for a luminous gas (or plasma) discharge to be generated when suitably energized. The electrode surfaces m be indicia-(or other graphic image-)shaped, thus producing a like shaped pattern of light of 10 sufficient visibility to be useful as a sign, indicator or other expression of visible informati

The pattern of at least one of the electr surfaces may be provided by a secondary manufactur for example, a user, through the means of painting

15 stencilling, silkscreening, lithography or the lik By so providing the latter electrode surfaces, the inherent difficulties and costs of producing signa (for example, using a heat-bent gas discharge tube conventional neon tube signs) are overcome, while

20 still producing a luminous gas image. Thus, even small signage producing enterprise, or home user, readily utilize the display device of the present invention to display a user desired image.

Additionally, the display panel of the 25 present invention is far more robust, durable and safe than its bent tube neon sign counterpart. I some configurations, the display device has transparent electrodes on both sides of the gas space, making the display device usable as a wind 30 or glass door simultaneously with its carrying im or information. The display panel may also find general usage in the architectural and outdoor illumination field, much as its bent tube neon sign counterpart does currently. Similarly, much as artists and designers use light filled tubes as components of graphic and sculptural statements, the light producing display devices of the invention may be used, with or without patterns to the illuminosity, as an artistic and design medium.

More particularly, in accordance with the invention, a display device includes first and second rigid, non-conductive sheet members, each having front and back surfaces, which may be substantially parallel. At least one of the first and second sheet members is transparent.

In a preferred form, the sheet members are substantially planar, but alternative configurations could be employed, such as similar cylindrical or spherical configurations. By way of example, the sheet members may be planar sheets of glass. The first sheet member may be substantially transparent and has a coating region on its front surface adapted to receive a first conductive coating on portions thereof. Typically, this first conductive coating represents the image to be displayed. The first conductive coating may be removable in part to correspond to a modified form of the image. The second sheet member may also be transparent. The first conductive coating may be applied by painting, stencilling, silkscreening, lithography, or the like. One or more spacer elements mutually position the first and second sheet members so that the back surface of the first sheet member is offset from and opposite the front surface of the second sheet member.

A discharge chamber is established by a gas impervious seal between portions of the back surface of the first sheet member and the front surface of the second sheet member. The discharge chamber defines a closed region in the gap between the back surface of the first sheet member and the front surface of the second sheet member. That closed region underlies at least in part the first conductive coating.

An electroluminescent gas is disposed within the closed region. While other gas mixtures may be used, in the preferred form the electroluminescent gas is a Penning gas mixture comprised substantially of 99% neon, 1% argon, and trace amounts (less than 0.1%) of mercury at a pressure of about 120 torr.

A second conductive coating is disposed on a portion of one of the front and back surfaces of the second sheet member underlying at least in part the closed region and a part of the coating region. An ajrplied drive voltage may be coupled between the fϋrst conductive coating and the second conductive coating to energize the device so that a luminous plasma image is established in the portions of the closed region between the overlying portions of those conductive coatings. In one form of the invention, the spacer includes at least one rigid spacer member disposed within the closed region and extending between the back surface of the first sheet member and the front 5 surface of the second sheet member.

In various embodiments, either or both of the first and second conductive coatings may be substantially translucent, transparent, reflective or opaque. Further, the conductive coating may be lø; disposed on the front surface of the second sheet member and at least in part within the closed region. Alternatively, the second conductive coating may be disposed on the back surface of the second sheet member and at least in part overlying the

15 closed region. A third non-conductive sheet member may overlie the second conductive coating opposite the back surface of the second sheet member. A fourth non-conductive sheet member may overlie the . first conductive coating. The latter non-conductive

20 sheets may be used to ensure that a user does not contact the electrodes during use. Further, those added sheets provide increased resistance to breakage of the device as a whole. Also, those sheets, when laminated to the first and second sheets, provide

25 increased stiffness of the chamber-defining walls so that relatively thin sheets may be used for the first and second sheet members, using relatively inexpensive (e.g. polycarbonate) material to form the third and/or fourth sheet members. In another form, the present invention includes one or more electroluminescent gas-filled enclosures. An electrode surface is disposed on one side of the gas space, and provision is made for coupling an externally applied effective capacitive plate on the other side of the gas space. With that configuration, a luminous gas (or plasma) discharge is generated in localized regions in the gas space near the external capacitive plate when the electrode is suitably energized and an external effective capacitive plate establishes a ground-coupled capacitance between that plate and the electrode, when the gas space is between those elements. Generally, the resultant pattern of light from the discharge has the shape of the effective plate of the capacitance.

The display device of the present invention may be constructed with the gas enclosures sandwiched between a pair of rigid members, providing a robust and durable device. Where those members have a planar sheet form, with at least one being transparent, the device is well suited for use as a dynamic interactive table or counter top or as a wall ^' or floor panel, with luminous patterns being generated in response to touching by a human user (which provides the effective external capacitive plates) .

In application, the device is useful in a variety of situations where proximity light control is desired, for example in direct interacting lighted walkways. These would consist of a sequence of gas filled panels each with a conductive plate underneath and a transparent nonconducting cover plate. The proximity and body capacitance of the person walking on the panel initiates a local gaseous discharge, which in turn generates light in the panel. A simple design consists of a sandwich construction of a metal plate at the bottom, a layer of uniformly spaced illuminable gas-filled tubes directly above this plate, and a top cover of tempered glass. The pressure of a person's body on the top cover is transmitted to the bottom plate, and then to any other vertical support means, by way of nonconducting vertical elements placed between the tubes with a height greater than the diameter of the tubes.

The display panel is also generally useful in the architectural and outdoor illumination field. Similarly, much as artists and designers use light filled tubes as components of graphic and sculptural statements, the light producing display devices of the invention may be used as an interactive artistic and design medium.

More particularly, in accordance with the invention, a display device includes an at least partially transparent first non-conductive sheet member having front and back surfaces. A base member, having front and back surfaces, and preferably a sheet material, includes an electrically conductive region. The base member may itself be electrically conductive, or a conductive film may be positioned on either the front or back surface of, or sandwiched between those surfaces of, the base member. In a preferred form, the sheet and base members are substantially planar, but alternative configurations could be employed, such as similar cylindrical or spherical configurations. By way of example, the sheet and base members may be parallel, planar sheets of glass, or polycarbonate, or acrylic or other material.

The sheet member may be substantially transparent and has a coupling region on its front suxface adapted to receive an externally applied, g-rouπd-cou led conductive member (such as a human hand) on portions thereof. Typically, this externally applied conductive member establishes the image to be displayed.

One or more spacer elements mutually position the sheet and base members so that the back surface of the sheet member is offset by a predetermined distance D from and opposite the front surface of the base member, and so that the conductive region of the base member underlies at least in part the coupling region of the sheet member.

A discharge chamber establishes one or more gas impervious chambers between portions of the back surface of the sheet member and the front surface of the base member. The discharge chambers define closed regions in the gap between the back surface of the sheet member and the front surface of the base member. Those closed regions lie at least in part between the coupling region of the sheet member and conductive region of the base member. An electroluminescent gas is disposed within the closed regions. While other gas mixtures may be used, in the preferred form the electroluminescent gas is a Penning gas mixture comprised substantially of neon at a pressure in the aproximate range 40-200 torr.

In a preferred form of the invention, the conductive region of the base member is formed by a conductive coating disposed on a portion of one of the front and back surfaces of the base member underlying at least in part the closed regions and a part of the coupling region of the sheet member. Alternatively, the base member may be a conductive material, such as an aluminum plate.

An applied drive voltage may be coupled between the conductive region of the base member and a reference (such as ground) potential to energize the device so that a luminous plasma image may be established in the portions of the closed region between the overlying portions of the conductive region and coupling region by the application of a ground-coupled external conductive member (such as a human hand) to the coupling region of the sheet member.

In one form of the invention, the spacer includes at least one rigid spacer member disposed within the closed region and extending between the back surface of the sheet member and the front surface of the base member. In various embodiments, the base member and its conductive region may be substantially translucent or transparent, reflective or opaque. In embodiments where the base member is conductive, or where the conductive region of the base member is established by a conductive film on the back surface of that base member, a non-conductive material may overlie the conductive region opposite the back surface of the base member. The latter non-conductive material may be used to ensure that a user does not contact the electrode during use. Further, that added material provides increased resistance to breakage of the device as a whole.

BRIEF DESCRIPTION OF THE DRAWINGS

The foregoing and other objects of this invention, the various features thereof, as well as the invention itself, may be more fully understood from the following description, when read together with the accompanying drawings in which:

Fig. 1 shows in exploded form, a display device according to the present invention;

Fig. IA shows, in section, the portion of the display device of Fig. 1 including the filling stem; Fig. 2 shows in exploded form, an alternative plasma device configuration;

Fig. 3 shows in perspecitve view, a plasma display device having a plurality of internal spacers; Fig. 4 shows in section along lines 4-4, the plasma display device of Fig. 3;

Fig. 5 shows a perspective view of an alternative spacer for use with the device of Figs. 3 and 4;

Figs. 6-9 show sectional views of alternative spacers for use with the device of Figs. 3 and 4;

Fig. 10 shows in exploded form, an alternative configuration for a plasma display device of the present invention;

Fig. 11 shows in perspective view, a display device according to an alternative form of the present invention; and

Fig. 12 shows, in section, the portion of the display device of Fig. 11.

DESCRIPTION OF THE PREFERRED EMBODIMENT

An exemplary luminous (plasma) panel display device 10 is shown in Fig. 1 in exploded form. The device 10 includes two flat and parallel non-conducting, transparent glass sheet members 12 and 14 having "front" surfaces 12a and 14a, respectively, and "rear" surfaces 14a and 14b, respectively. As shown, sheet members 12 and 14 are substantially planar, but other forms might also be used, such as cylindrical or conical. An edge seal and spacer element 16 defines an enclosed hermetic volume (or region) 20 having an electroluminescent gas therein. Overlapping conductive coatings 26 and 28 are disposed on the front surface 12a of sheet member 12 and on the rear surface of 14b of sheet member 14, respectively.

A filling stem 22, extending parallel to the principal plane of volume 20, passes between opposing portions of sheet members 12 and 14 and through spacer member 16 to provide access to chamber volume Z0. The outer diameter of filling stem 22 is less than or equal to the distance between the front surface 12a and the back surface 14b. This filling stem 20 permits evacuation and back-filling of the volume 20 following assembly of sheet members 12, 14 and seal/spacer element 16. After back-filling is accomplished, the stem 22 is sealed off. In alternative embodiments, different filling stem configurations may be used. For example, the stem may be placed through a hole drilled through sheet member 12 and fused to the edges of that hole, with the central axis of the stem extending perpendicular to the principal plane of volume 20.

In the preferred embodiment, the sheet members 12 and 14 are soda-lime planar glass sheets. The spacer element 16 is also soda-lime glass. The thickness of the sheets is determined to establish (1) a parallel orientation of the two sheets, producing a gas-enclosing space with uniform gap after filling, and (2) total mechanical and thermal stress on the glass sheet members during the assembly and evacuation of the device 10 which does not exceed the properties of the glass, causing breakage. The preferred embodiment has an enclosed volume which is 15 cm by 15 cm, with an intersheet gap in the range 5 0.25 - 1.0 mm, as established by spacer 16. The soda-lime glass sheet members 12 and 14 are 3.0 mm thick. With larger surface areas, thicker glass sheets may be used, and for smaller areas, thinner glass may be used. For glass with higher resistance

10 to temperature stressing and higher mechanical strength, such as borosilicate glass, the thickness required for any specific surface area may also be reduced im comparison to the soda-lime glass sheets used in the illustrated embodiment. For example, a

15 15 cm by 15 cm chamber formed by Pyrex brand borosilicate glass sheets with a 1 mm gap, may have 2.5 mm sheet thickness without overstressing.

While the present embodiment is a three element construction (i.e. sheet members 12, 14 and

20 spacer element 16), other configurations might also be used, for example, two sheet members in a sandwich configuration where one or both of the adjacent surfaces includes an etched chamber-defining region. In the latter configuration, the peripheral spacer is

25 integral with at least one of the sheet members.

In general, spacing and sealing of the chamber 20 of device 10 is provided by a perimeter seal. Various means of hermetically sealing the sheets 12 and 14 and spacer 16 may be used. For 30 example, vacuum epoxy and conventional sealing glasses are suitable. In the illustrated embodiment, the 15 cm by 15 cm panel 10 uses a 1 mm thick, 1.5 cm wide spacer element 16 which is disposed about the periphery of chamber 20. The sealing is performed with unloaded, 100% solids, Type 360T vacuum epoxy formulated and sold by Epoxy Technology of Waltham, - Massachusetts. The epoxy seal is obtained with a 10 minute oven bake at 120 degrees C. With this seal, outgassing is less than 5 X 10^~9 cc/sec, giving the panel 10 a life on the order of at least 6 months.

As; an alternative to vacuum epoxy, Corning

Fyrocerairr brand sealing glass powder, code 7575, may be used to seal soda-lime sheets 10 and 12 to each other using .25 to 1.0 mm thick glass spacers. With this method of sealing, the powdered sealing glass is applied as a slurry with a nitrocellulose binder dissolved in a vehicle such as amyl acetate. The binder and vehicle are burned off at 350 degrees C, and the sealing is accomplished at 450 degrees C during a 60 minute bake. Slow cooling is used to provide a relatively stress free panel with substantially no seal outgassing. Panel life of glass sealed panels is limited by the outgassing of the glass itself and sputtering and gas cleanup, some of which can be greatly reduced by vacuum baking and the inclusion of sputtering reducing vapors such as Hg into the gas fill.

Regardless of which sealing techniques are used, careful cleaning of all surfaces is performed, using conventional techniques prior to assembly and 0 sealing of the sheets 12 and 14. For example, a sequence of water and solvent washes with detergents, distilled and deionized water rinses, vapor degreasing and warm air drying are perfectly performed prior to sealing of the panel 10.

Many gases, gas mixtures and gas pressures 5 may be used in the volume 20 to achieve various colors and intensities of light output using ac drive voltages in the range of 280 to 1800 volts, from 5: kHz to 10 MHz, using sine and square wave signals and. complex waveforms. Generally, the

IDS electroluminescent gas in chamber 20 is a mixture of noble gases with additions of small quantities of secondary gases to create Penning mixes. In the preferred embodiment, a very effective gas fill with maximum intensity of about 100 lumens at a drive

15 power level of 1.5 watt/cm² is a Penning mixture made with 99% neon, 1% argon, and trace amounts (less than 0.1%) of mercury, filled to a pressure of about 120 torr. Nitrogen could be substantial for the argon in this exemplary mix. The color of the light output

2₀ from this panel fill is orange-yellow at maximum brightness (using a photo-optically calibrated sensor) but may be varied slightly by changing the frequency and waveform of the driving ac signal, from yellow-orange to orange-red, with a loss in

25 brightness.

To establish the electroluminescent gas in the enclosed volume 20, the panel 10 is first evacuated through the filling stem 22, as coupled to a vacuum pump through a gas filling system with the 30 suitable filters, pressure and vacuum gauges and compressed gas regulators and valves. In the present embodiment, as the filling stem 22 is established prior to assembly of sheet members 12 and 14 and spacer element 16 by first milling matching conical void regions 23a and 23b in opposing portions of the 5 periphery of sheet members 12 and 14, and a hole is cut in the corresponding portion of the spacer element 16. As shown in Fig. IA, the tubular filling stem 22 is then placed into and sealed to the channel established by the conical void regions and spacer

10. holes at the time of assembly and sealing of sheet members 12. and 22 and spacer element 16. The interior 22a of stem 22 is contiguous to volume 20. Thus, the stem 22 is sealed to the panel 10 with a through channel to the interior space (i.e. volume

15 20) formed by the combination of the sheet members 12 and 14 and the spacer element 16. In the preferred embodiment, filling stem 22 is attached to the device 10 with low vapor pressure epoxy or with sealing glass.

20 In alternate embodiments, the stem 22 may extend through one of sheet members 12 and 14 in a direction perpendicular to the sheet member. To establish such a filling stem, a small hole is diamond drilled through the sheet member and the stem

25 end is flared and ground flat on the sealing surface prior to attachment. The stem is then attached using sealing glass or epoxy.

The use of conductive coatings 26, 28 on the glass sheets 12, 14 allows the panel 10 to illuminate 30 when attached to a source of driving voltage. There are several ways to configure the conductive coatings, depending on the desired visual and operational properties of the final panel 10. The panel 10, as shown in Fig. 1 has two conductive coatings 26 and 28, one attached to each of the outer surfaces of the transparent sheets 12, 14 with the electroluminescent gas located between the sheets and not in contact with either coating. Three basic types of conductive coatings identified by their optical properties may be used; namely, translucent, transparent, reflective, and opaque.

Transparent conductive coatings pass light, and have little or no color, thus making the coating invisible to the eye. Examples of this kind of coating are vacuum evaporated or sputtered metal films, usually gold or aluminum, and indium doped tin oxide films, either sputtered or chemically deposited on the glass sheet. The coating may be applied in a uniform fashion or may be applied as a pattern. Suitable coatings have resistivities on the order .1 to 100 ohms/square, are thermally stable at sealing temperatures and are generally scratch and chemically resistant. Etching the coating into patterns for use in defining the illumination zone of the panel may be done by the use of silkscreened, painted or stencilled patterns of resist followed by coating removal with chemical (acid or basic) solutions with local or general application, i.e. bath, spray or wipe, or by mechanical means such as abrasion or scraping. Reflective conductive coatings reflect light, or reflects some percentage of the light falling on it, and are generally partially transparent and partially reflective. Examples are 5 aluminum, chromium, silver or gold coatings with a reflectivity over 10%. The coatings are applied by sputtering, evaporation, chemical deposition or mechanical means, i.e. embossing, and may be applied as patterns or may be uniform and continuous. The ID_. resistivity varies from .01 to 10 ohms/square for the αaatings, and they are generally capable of withstanding sealing temperatures and processing. The coating may be patterned for use as a sign or indicator as described above.

15 Opaque conductive coatings do not allow the penetration of light to any significant extent. Such coatings allow the view of the gas discharge from one direction only, and give it a higher contrast background. The coating is generally of a paint or

20 ink type consisting of a vehicle, a binder and a conductive component in suspension such as nickel oxide, nickel metal powder, graphite, or mixes of these materials. It may be applied by spraying, rolling, brushing or any of a host of mechanical or

25 chemical means, either as a uniform and continuous coating or as a pattern.

In the embodiment of Fig. 1, front surface 12a of sheet member 12 is adapted to receive the first (indicia-shaped) conductive coating 26. The 30 back surface 14b of coating 14 supports the second conductive coating 28. Electrical contact to the coatings 26, 28 may be made directly, for example, by wiper arms (not shown) or conductive epoxy (not shown) , in a manner permitting an applied drive voltage to be applied across those coatings. The various coatings 26, 28 may each be of the transparent, reflective or opaque type, depending upon the desired luminous image characteristics.

By way of example, in the illustrated configuration, the film coating 28 is a transparent 100 ohms per square deposited indium doped tin oxide film coating 28. As shown in Fig. 1, the front surface 12a has received, by silkscreening, a nickel-graphite colloidal suspension coating 26 (e.g. Type 401 conductive paint, manufactured by Acheson Colloids, Inc.). With this configuration, a 30 kHz, 900 volt sinusoidal signal applied across coatings 26 and 28 provides a yellow-orange-colored "A"-shaped display. The configuration illustrated in Fig. 1 is particularly well adapted to receive coating 26 by conventional processes such as silkscreening and the like, due to the overall planar structure of device 10, where the filling stem 22 lies substantially in the same principal plane as the device 10.

Fig. 2 shows a display device 10' similar to that in Fig. 1 where corresponding elements are identified with the same reference designations as in Fig. 1. In Fig. 2, a conductive border strip 30 is disposed on the peripheral portion of the front surface 12a of sheet 12. The border strip 30 is connected to coating 26 by portions 30a and 30b. With this configuration permits a simple connection (at contact 44) for coupling to an externally applied signal.

The embodiment of Fig. 2 also includes a third non-conductive sheet 40 overlying the back surface 14b of sheet 14. Sheet 40 provides an electrical insulation layer for the embodiment of Fig. 2 to protect a user from contacting a drive voltage applied to coating 28, relative to the JJQ; grounded coating 26. A connector 46 is positioned on sheet 40 and feeds through to coating 28 to provide a convenient means for coupling a drive signal to coating 28. Otherwise, the embodiment of Fig. 2 is similar to and operates in the same manner as the 15 embodiment of Fig. 1.

Figs. 3 and 4 show a similar configuration to the embodiment shown in Fig. 2, but further including eight raised spacers 55-62 projecting from sheet 12 and extending to sheet 14, all within the

20 enclosed volume 20. The spacers permit a relatively large area pair of sheet members to be used while still retaining a relatively high level of structural rigidity. The spacers also permit use of a relatively broad range of gas pressures in chamber

25 20. The spacers 55-62 as shown are cylindrical in shape. Alternative forms for those spacers are shown in section in Figs. 5-9. In the preferred form of the invention, as shown in Fig. 4, the raised spacers extend only part way between the surfaces 12b and 14a when enclosed volume 20 is filled with electroluminescent gas. With this configuration, during assembly of near-atmospheric pressure (in enclosed volume 20) embodiments, volume 20 can be evacuated and the raised spacers will play a limit on the resultant displacement of the sheet members 12, 14, thereby permitting use of relatively thin sheet members 12, 14.. Then, after backfilling with the electroluminescent gas, the raised spacers again extend only partially between surfaces 12b and 14a, permitting a substantially uniform luminescent display across the entire enclosed volume 20.

Another embodiment, device 60, is shown in Fig. 10. Device 60 is similar to that shown in Fig. 1, except that the coating 28 is disposed on the front surface 14a of sheet 14. With this configuration, there is no need for the third sheet 40 since the drive electrode is fully within the enclosed volume 20. Electrical contact is made to coating 28 by a portion 28a which extends beyond the seal/spacer element 16.

Here, the coating 28 is in direct contact with the gas in chamber 20. While better electrical coupling is achieved between coating 28 and the gas, a lower drive voltage may be used and increased edge definition for the image is attained, compared with embodiments where coating 28 is on the back surface 14b. There is, however, a somewhat reduced lifetime of the device due to sputtering that occurs at the coating 28. An alternative luminous (plasma) display device 110 is shown in Fig. 11 in perspective form and in Fig. 12 in section. The device 110 includes two flat and parallel non-conducting, transparent sheet members 112 and 118 having "front" surfaces

112a and 118a, respectively, and "rear" surfaces 112a and 118b, respectively. As shown, sheet members 112 and 118 are substantially planar, but other forms might also be used, such as cylindrical or conical.

In the preferred embodiment, sheet (or base) membex 12 is a one foot by four feet, 3/16 inch thick polycarbonate (Lexan™) panel. Sheet member 112 bears a conductive coating 114 on its front surface 112a. In the preferred embodiment, coating 114 is provided by nickel oxide spray paint, such as-

E-Kote™ 63 Nickel Conductive Paint manufactured by Acme Chemicals and Insulation Co, New Haven, Connecticut.

Sheet member 118 is a one foot by one foot, 1/4 inch thick thermally tempered glass panel positioned so that its bottom (or back) surface 118b is opposite and spaced apart by a predetermined distance D (7/8 inch in the preferred embodiment) fxom the coating 114 front surface 112a of sheet member 112. In the preferred form of the invention, this spatial relationship of sheet members 112 and 1!18^: is established by non-electrically conductive peripheral support members 120, 122, 124 and 126. In the embodiment of Fig. 11, those support members 120, 122, 124 and 126 are constructed of high modulus wood such as oak. Other non-conductive materials may readily be used to form a fully enclosed region between surfaces 112a and 118b. A set of nine 46 inch long, 1/2 inch inner diameter, 3/4 inch outer diameter, closed end, cylindrical Pyrex glass tubes 130a-130i are positioned in parallel within the space between surfaces 112a and 118b. Each of the tubes 130a-130i provides an enclosed interior region which is filled with an illuminable, or electroluminescent, gas. In the illustrated form of the invention, the gas is neon at a pressure of 88 torr. Pressures in the range of 40-200 torr might also be used, although other gas mixtures and pressures may be used for these and other sized tubes.

The tubes 130a-130i are maintained at a substantially uniform spatial separation by rigid, non-electrically conductive spacers 136a-136h at each end of the region between surfaces 112a and 118b and at uniformly spaced locations along the length of tubes 130a-130i. The spacers 136a-136h have a dimension equal to one inch in the direction perpendicular to surfaces 112a and 118b and provide support to keep the sheet members 112 and 118 in position, even as external forces are applied to those sheet members.

The resultant configuration for display panel 110 is a rugged device suitable to support the weight of a person or for use as a table or bar-top. The device might also be constructed without the spacers, depending on forces expected to be encountered. In operation, an AC signal generator 140 provides a 9 KV, 38 KHz excitation voltage to the conductive coating 114 relative to ground potential. Under these conditions, a person may bring his hand, for example, to the front surface 118a of sheet member 118, as illustrated in Fig. 11. Where that hand is on or near the surface 118a, a capacitive effect causes the AC electric field from the region of coating 114 underlying the hand to pass from that regjior. of the coating to the hand and then to ground pot.enti:a2.l.. That field, as it passes through the interior region of the portions of tubes 130a-130i underlying the hand, causes the gas in those and adjacent interior regions to produce a glow discharge. The extent of the image beyond the outline of the conductive member depends in part on the gas pressure and applied frequency and voltage, and distance of the conductive member from the surface 118a.

Thus, the use of conductive coating 114 on the glass sheets 112 allows the panel 110 to illuminate when attached to a source of driving voltage and a suitable ground-coupled conductive member is positioned proximal to surface 118a. There are several ways to configure the conductive coating 114, depending on the desired visual and operational properties of the final panel 110. The panel 110, as shown in Fig. 11 has a conductive coating 114 on the "inner" surface of the sheet 112 with the electroluminescent gas located between the sheets 112 and 118. Three basic types of conductive coatings identified by their optical properties may be used; namely, translucent or transparent, reflective, and opaque.. Transparent conductive coatings pass light, and have little or no color, thus making the coating invisible to the eye. Examples of this kind of coating are vacuum evaporated or sputtered metal films, usually gold or aluminum, and indium doped tin oxide films, either sputtered or chemically deposited on the glass sheet. The coating may be applied for use with a transparent, reflective or opaque base member.

Reflective conductive coatings reflect light, or reflects some percentage of the light falling on it, and are generally partially transparent and partially reflective. Examples are aluminum, chromium, silver or gold coatings with a reflectivity over 10%. The coatings may be applied by sputtering, evaporation, chemical deposition or mechanical means, i.e. embossing, and may be applied as patterns or may be uniform and continuous. The resistivity varies from .01 to 10 ohms/square for the coatings.

Opaque conductive coatings do not allow the penetration of light to any significant extent. Such coatings allow the view of the gas discharge from one direction only, and give it a higher contrast background. The coating is generally of a paint or ink type consisting of a vehicle, a binder and a conductive component in suspension such as nickel oxide, nickel metal powder, graphite, or mixes of these materials. It may be applied by spraying, rolling, brushing or any of a host of mechanical or chemical means. This embodiment represents one form of the invention. The parameters variables of gas containment method, gas mixture, gas pressure, capacitor charging voltage, drive voltage frequency and amplitude and general panel geometry may all be selectively varied to provide desired variations in the operation and visual characteristics of the invention.

The invention may be embodied in other specific forms without departing from the spirit or essential characteristics thereof. The present embodiments are therefore to be considered in all respects as illustrative and not restrictive, the scope of the invention being indicated by the appended claims rather than by the foregoing description, and all changes which come within the meaning and range of equivalency of the claims are therefore intended to be embraced therein.

What is claimed is:

Claims

1. A luminous panel display device comprising:

A. a first rigid, non-conductive sheet member having front and back surfaces, said first sheet member having a coating region on portions of its front surface, said coating region being adapted to receive a first conductive coating representative of a predetermined image;

B. a second rigid, non-conductive sheet member having front and back surfaces, wherein at least one of said first and second sheet members is transparent;

C. spacer means for mutually positioning said first and second sheet members whereby the back surface of said first sheet member is offset by a predetermined separation from and opposite the front surface of said second sheet member;

D. discharge chamber means for establishing a gas impervious seal between portions of the back surface of said first sheet member and the front surface of said second sheet member to define a closed region in the gap between said back surface of said first sheet member and the front surface of said second sheet member and underlying said coating region;

E. electroluminescent gas disposed within said closed region; and F. a second conductive coating disposed on a portion of one of the front and back surfaces of said second sheet member underlying at least in part said closed region and a portion of said coating region.

2. A display device according to claim 1 further comprising said first conductive coating disposed upon said coating region.

3. A display device according to claim 2 wherein portions of said first conductive coating are removable whereby said first conductive coating may be representative of a modified form of said predetermined image.

4. A display device according to claims 1 or 2 wherein said front and back surfaces of said first sheet member are substantially parallel.

5. A display device according to claim 4 wherein said front and back surfaces of said second sheet member are substantially parallel.

6. A display device according to claims 1 or 2 wherein said front surface of said first sheet member and said back surface of said second member are substantially planar and mutually parallel.

7. A display device according to claim 6 further comprising a tubular filling stem extending through said seal of said discharge chamber means whereby the region interior to said stem is contiguous with said closed region.

8. A display device according to claim 7 wherein said stem has an outer diameter less than or equal to the distance between front surface of said first sheet member and the back surface of said second sheet member.

9. A display device according to claims 1 or 2 further comprising a tubular filling stem extending through said seal of said discharge chamber means whereby the region interior to said stem is ; contiguous with said closed region.

10. A display device according to claims 1 or 2 further comprising means for coupling an applied drive voltage across said first conductive coating and said second conductive coating.

11. A display device according to claim 10 wherein said coupling means comprises a third conductive coating, said third conductive coating being disposed on a peripheral region of said front surface of said first sheet member and including at least one extension portion extending to said coating region.

12. A display device according to claims 1 or 2 wherein said second sheet member is substantially transparent.

13. A display device according to claims 1 or 2 wherein said first and second sheet members are glass.

14. A display device according to claims 1 or 2 wherein said spacer means includes said discharge chamber means and further includes at least one rigid spacer member disposed within said closed region and

5 extending from one of said back surface of said first sheet member and said front surface of said second sheet member and toward the other of said surfaces.

15. A display device according to claim 14 wherein said rigid spacer members extend less than

ID? the- full distance between said back surface of said first sheet member and said front surface of said second sheet member when said electroluminescent gas is at a predetermined pressure in said closed region.

16. A display device according to claims 1 or 2 15 wherein said electroluminescent gas is a Penning gas mixture.

17. A display device according to claim 16 wherein said gas mixture is comprised of approximately 99% neon, 1% argon and less than 0.1%

20 mercury at a pressure equal to approximately 120 torr.

18. A display device according to claims 1 or 2 wherein said first conductive coating is substantially transparent.

19. A display device according to claims 1 or 2 25 wherein said first conductive coating is substantially reflective.

20. A display device according to claims 1 or 2 wherein said first conductive coating is substantially opaque.

21. A display device according to claims 1 or 2 wherein said second conductive coating is substantially transparent.

22. A display device according to claims 1 or 2 wherein said second conductive coating is substantially reflective.

23. A display device according to claims 1 or 2 wherein said second conductive coating is substantially opaque.

24. A display device according to claims 1 or 2 wherein said second conductive coating is disposed on said front surface of said second sheet member and at least partially within said closed region.

25. A display device according to claims 1 or 2 wherein said second conductive coating is disposed on said back surface of said second sheet member and at least partially overlying said closed region.

26. A display device according to claim 24 further comprising a third non-conductive sheet member opposite said back surface of said second sheet member and overlying said second conductive coating.

27".. A display device according to claims 1 or 2 wherein, sard: first sheet member is substantially transparent.

28. An interactive luminous display device comprising:

A. an at least partially transparent, non-conductive sheet member having front and back surfaces.,., said first sheet member having a coupling reg_.iOTB an portions of its front surface, said coupling region being adapted to receive thereon an externally applied conductive member;

B. a base member having front and back surfaces, and including an electrically conductive region;

C. spacer means for mutually positioning said sheet member and said base member whereby the back surface of said sheet member is offset by a predetermined distance from and opposite the front surface of said base member and said conductive region of said base member underlies at least a portion of said coupling region of said sheet member;

D. discharge chamber means for establishing at. l a^'st one gas impervious chamber between portions of the. back surface of said sheet member and the front surface of said base member, said chambers defining closed regions in the gap between said back surface of said sheet member and the front surface of said base member and lying at least partially between said coupling region and said conductive region of said base member; and

E. electroluminescent gas disposed within said closed regions.

29. A display device according to claim 28 further comprising means for coupling an applied a.c. drive voltage between said conductive region and a reference potential, and

wherein said device is responsive to a ground potential-coupled conductive member positioned proximal to said coupling region to generate a luminous gas discharge in the portions of said closed regions between said conductive member and said conductive region of said base member.

30. A display device according to claim 28 wherein said front and back surfaces of said first sheet member are substantially parallel.

31. A display device according to claim 30 wherein said front and back surfaces of said base member are substantially parallel.

32. A display device according to claim 28 wherein said front surface of said first sheet member and said back surface of said base member are substantially planar and mutually parallel.

33. A display device according to claim 28 wherein said base member is substantially transparent.

34. A display device according to claim 28 wherein said sheet member and said base member are materials from the group consisting of glass and polycarbonate.

35. A display device according to claim 28 wherein said spacer means includes said discharge chamber means and further includes at least one rigid spacer member disposed within said closed region and extending from one of said back surface of said sheet member and said front surface of said base member and toward the other of said surfaces.

36. A display device according to claim 35 wherein said rigid spacer members extend less than the full distance between said back surface of said sheet member and said front surface of said base member when said electroluminescent gas is at a predetermined pressure in said closed region.

37. A display device according to claim 28 wherein said electroluminescent gas is a Penning gas mixture.

38. A display device according to claim 37 wherein said gas mixture is comprised substantially of neon at a pressure in the approximate range 40-200 torr.

39. A display device according to claim 28 wherein said base member including said conductive region and is substantially transparent.

40. A display device according to claim 28 wherein said base member including said conductive region is substantially reflective.

41. A display device according to claim 28 wherein said base member including said conductive region is substantially opaque.

42. A display device according to claim 28 wherein said base member is a ^"sheet and said conductive region is a film disposed on said back surface of said base member and at least partially underlying said closed region.

43. A display device according to claim 42 further comprising a third non-conductive sheet member opposite said back surface of said base member and underlying said conductive region.

44. A display device according to claim 28 wherein said first sheet member is substantially transparent.

45. A display device according to claim 28 wherein said second sheet member includes means for reflecting light incident on said front surface of said second sheet member.

46. A display device according to claim 28 wherein said chamber means comprises at least one transparent, elongated tubular member, said tubular member being sealed at each end thereof.

47. A display device according to claim 28 wherein said sheet member and said base member are substantially planar and parallel rigid sheets, and wherein said chamber means comprises a plurality of transparent elongated tubular members, said tubular members being sealed at each end thereof.

48. A display device according to claim 47 wherein said tubular members are cylindrical.

49. A display device according to claim 47 wherein said tubular members have substantially parallel central axes, and

wherein the outer diameter of said tubular members is less than said predetermined distance.

50. A display device according to claim 49 further comprising spacing members positioned between at least two of said tubular members, said spacing members having a dimension in the direction between said first and second sheet members substantially equal to said predetermined distance.